Metal bonded structure and metal bonding method

Abstract

After a microcrystalline layer having a grain size that is finer than that of a base member is formed on the surface of at least one of a first bonding portion and a second bonding portion, the gap between the first bonding portion and the second bonding portion is filled with a solution into which copper oxide can be eluted, so as to deposit copper oxide contained in the surface oxide film into the solution. By applying pressure and by heating at a temperature of at most the copper recrystallization temperature, the components contained in the solution are removed except for copper, so as to elute copper oxide, thereby bonding the first bonding portion and the second bonding portion via the copper thus deposited. Subsequently, the copper is solid-phase diffused into the first bonding portion and the second bonding portion.

What is claimed is: 
     
       1. A metal bonding method for bonding a first metal and a second metal each including copper as a principal component, the method comprising:
 forming a layer on at least one of the first metal and the second metal, the layer including copper as a principal component and having a copper crystal grain size smaller than that of the first metal and the second metal; 
 after the layer is formed, filling a gap between the first metal and the second metal with a solution into which oxide including a copper oxide is eluted; 
 pressing the first metal and the second metal against each other to reduce the gap after the gap is filled with the solution; and 
 applying heat to the gap to a temperature equal to or lower than a copper recrystallization temperature, with the first metal and the second metal pressed against each other. 
 
     
     
       2. The metal bonding method according to  claim 1 , wherein the layer forming step includes polishing a surface of the at least one of the first metal and the second metal to form the layer on the surface. 
     
     
       3. The metal bonding method according to  claim 1 , wherein the solution is inactive with respect to copper. 
     
     
       4. The metal bonding method according to  claim 2 , wherein the solution is inactive with respect to copper. 
     
     
       5. The metal bonding method according to  claim 1 , wherein the solution contains a ligand that forms a complex with copper. 
     
     
       6. The metal bonding method according to  claim 2 , wherein the solution contains a ligand that forms a complex with copper. 
     
     
       7. The metal bonding method according to  claim 3 , wherein the solution contains a ligand that forms a complex with copper. 
     
     
       8. The metal bonding method according to  claim 5 , wherein the complex is thermally degradable. 
     
     
       9. The metal bonding method according to  claim 6 , wherein the complex is thermally degradable. 
     
     
       10. The metal bonding method according to  claim 7 , wherein the complex is thermally degradable. 
     
     
       11. The metal bonding method according to  claim 1 , wherein the solution is ammonia water or a carboxylic acid aqueous solution. 
     
     
       12. The metal bonding method according to  claim 2 , wherein the solution is configured as ammonia water, or otherwise as a carboxylic acid aqueous solution. 
     
     
       13. The metal bonding method according to  claim 3 , wherein the solution is ammonia water or a carboxylic acid aqueous solution. 
     
     
       14. The metal bonding method according to  claim 4 , wherein the solution is ammonia water, or a carboxylic acid aqueous solution. 
     
     
       15. The metal bonding method according to  claim 5 , wherein the solution is ammonia water or a carboxylic acid aqueous solution. 
     
     
       16. The metal bonding method according to  claim 6 , wherein the solution is ammonia water, or a carboxylic acid aqueous solution. 
     
     
       17. The metal bonding method according to  claim 7 , wherein the solution is ammonia water or a carboxylic acid aqueous solution. 
     
     
       18. The metal bonding method according to  claim 8 , wherein the solution is ammonia water or a carboxylic acid aqueous solution. 
     
     
       19. The metal bonding method according to  claim 9 , wherein the solution is ammonia water or a carboxylic acid aqueous solution. 
     
     
       20. The metal bonding method according to  claim 1 , wherein the layer forming step including performing sputtering to form the layer on the at least one of the first metal and the second metal. 
     
     
       21. The metal bonding method according to  claim 1 , wherein the layer forming step includes performing plating to form the layer on the at least one of the first metal and the second metal. 
     
     
       22. The metal bonding method according to  claim 1 , wherein the layer forming step includes applying strain to a surface of the at least one of the first metal and the second metal to form the layer.